I was in a hardware store today buying fuel for my combustion gun, and I noticed that the new larger diameter yellow Bernzomatic fuel tanks are called "Max Power Propylene" rather than MAPP gas. I went home and looked up the MSDS sheet, and it turns out the new bottles contain 99.5% Propylene and 0.5% Propane, as opposed to the original 56% LPG/44% Propadiene/Methyl Acetylene MAPP gas blend. Further investigation shows that Bernzomatic no longer produces MAPP at all.

I don't know why they switched over, but I figured it would be interesting to all of the current MAPP users on the forum. As far as performance goes, I expect it to be similar to the original stuff in terms of both heat energy production and flame front speed. I purchased a bottle to test, since I have found the faster burn rate of unsaturated hydrocarbons to be beneficial in cannons with oversized chambers, such as my large combustion gun.

Be aware that propylene has a higher vapor pressure than propane. The relief valves used for propane tanks vent at too low of a temperature and has caused some hot weather accidents. Here is a chemical safety board investigation into one of these fires. Never leave one of these in your car in hot weather or on a sunny day. Often this stuff is put into the same batch of cylinders that propane is shipped in.

According to a conversation I overheard in the local welding supply shop near my house, they stopped with the MAPP because it was a byproduct in a production of a specific petroleum product that they nolonger are making. They have been selling off the excess MAPP for several years now, and they supplies are drying up. Buy it now while you can!

As I said, I don't know this as fact, it is just what I overheard a year ago.

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Lentamentalisk wrote:According to a conversation I overheard in the local welding supply shop near my house, they stopped with the MAPP because it was a byproduct in a production of a specific petroleum product that they nolonger are making. They have been selling off the excess MAPP for several years now, and they supplies are drying up. Buy it now while you can!

As I said, I don't know this as fact, it is just what I overheard a year ago.

That makes sense, I have noticed that MAPP has been slowly disappearing from hardware store shelves over the past year or so, even before the Propylene started appearing. I guess that means the end of MAPP as a spudgun fuel is imminent, just as the original Right Guard used by spray n' prayers disappeared from use a couple years after they changed the formula.

That said, Propylene should be a good replacement. The burn rate and heat production are nearly identical, and the price is pretty much the same. I'll miss the psychological effect of burning triple bonded hydrocarbons (Methyl Acetylene) in my launchers, but that's easy to get over.

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